Development conditions: The solvent is allowed to migrate until the front reaches a line 15 cm from the starting line.

Detection: The plate is left in a chromatographic chamber containing some iodine crystals until spots appear.

Results: The spot obtained from the solution of the sample subjected to procedure A and the spot obtained from the reference solution of acetylsalicylic acid display the same chromatographic characteristics of migration and detection. No secondary spots are revealed.

The spot obtained from the solution of the sample subjected to procedure B and the spot obtained from the reference solution of salicylic acid display the same chromatographic characteristics of migration and detection. There is no longer a spot corresponding to acetylsalicylic acid.

Colorimetric determination

To 10 ml of a 0.1% solution of the substance in water, add 1 ml of ethanol 95%, 5 ml of 1% ferric nitrate solution (9H2O) in 1% nitric acid, and dilute to 100 ml with water.

After procedure A:

no violet coloration.

After procedure B:

very intense violet coloration. By comparison with a reference concentration series of salicylic acid, the degradation was assessed at 75%.

Conclusion

No decomposition is detected by thin-layer chromatography after procedure A, but after procedure B, the substance is completely degraded.